Centrifugal balance fuel valve for rotating combustion products generators



May 13, 1952 T. B. MuRDocK E-rAL 2,596,161

CENTRIFUGAL BALANCE FUEL VALVE F OR ROTATING coMBusTIoN PRODUCTS GENERAToRs Filed Sept. 16, 1949 #Cm d im w ./.lM/Alldllk Inventors z /4' Thomas B. Murdock',

f, Richard H. Ban.,

' by ThehA Abbovneg.

Patented May 13, 1952 UNITED STATES PATENT OFFICE CENTRIFUGAL BALANCE FUEL VALVE FOR ROTATING 'COMBUSTION PRODUCTS GEN- ERATORS Application September 16, 1949, Serial No. 116,024

(Cl. Gil-39.28)

v 3 Claims.

Our invention relates to a fuel supply system and, more particularly, to a fuel supply system of the type utilized to supply fuel under variable pressure to a reaction motor carried on the tip of a helicopter rotor blade.

In supplying `a fuel to a reaction motor located at the tip of a rotating blade, a problem arises in that the fuel which is carried in the fuel line running from the hub of the rotorto the tip of the rotor blade has a centrifugal pressure head developed from the rotation of the rotor blade. As a result of this pressure head, the fuel delivered to the reaction motor is at a pressure which is equal in magnitude to the fuel pump pressure and the centrifugal pressure head. Since the centrifugal pressure head is dependent on the angular Velocity of the rotating blade, the pressure of the fuel delivered to the reaction motor varies with the speed of the rotating blade. The reaction motor requires fuel under controlled pressure, and, therefore, it is necessary to provide a means to compensate automatically for the centrifugal pressure head.

It is, therefore, an object of our invention to provide a fuel supply system which is solely responsive to the fuel pump pressure regardless of the magnitude of the centrifugal pressure `head even though it be much greater than the fuel pump pressure.

The novel features which we believe to be characteristic of our invention are set forth with particularity in the appended claims. The invention itself, however, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l shows a reaction motor powered helicopter rotor having a fuel supply system embodying our invention; Fig. 2 is a cross sectional VieW showing constructional details of the fuel supply Valve shown diagrammatically in Fig. l; Fig. 3 is a section taken along the line 3-3 of Fig. 2; Fig. 4 is a section taken along the line 4--4 of Fig. 2; and Fig. 5 shows a cross sectional view of a modification of the fuel supply valve of our invention.

Referring to Fig. 1 of the drawing, we have shown diagrammatically a jet powered helicopter rotor comprising a lifting blade I extending from the hub 2 and carrying adjacent to its outer tip reaction motor 3. Mounted substantially concentrically with the center f rotation of the rotor assembly is a fuel pump 4 whose discharge is controlled by a suitable control 5 which is operated by the pilot. The fuel pump 4 is manifolded to fuel supply lines 6 and delivers fuel at varying pressures. The fuel supply line 6 is carried within the lifting blade I and runs the length of the blade towards the tip to fuel valve 'I which is mounted at the same radius from the hub as the reaction motor 3 substantially in the position indicated. Connected to the outlet of the fuel valve 'I, is a fuel conduit 8 leading to the ccmbustion chamber of reaction motor 3.

Referring to Fig. 2 of the drawing, which is a cross sectional view of the valve shown conventionally in Fig. l, we have shown the valve as comprising a valve barrel 9, which has a valve guide section Ill supported therein by septum II. The valve guide section Ill and septum II divide the valve barrel into an inlet pressure chamber I2 and an outlet pressure chamber I3 which are respectively connected to the fuel supply line 6 and fuel conduit 8 by inlet aperture I4 and outlet aperture I5. Located within the inlet pressure chamber I2 is a weighted valving piece I6 which cooperates in action with valving piece I'I, located in the outlet pressure chamber I3, through valve stem I8. The mass of valving pieces I6 and I'I and the valve stem I8, which comprise the moving parts of the centrifugal balance Valve l, are selected of such size that their total mass has a centrifugal force equal to the centrifugal force of the fuel in the fuel line. It is important that a sufficient clearance be provided between the valving pieces I6 and I'I and the valve barrel 9 to permit the fuel pressure in each of the pressure chambers to be exerted on the end pieces I9 and 2U and the outer faces of valving pieces I6 and I'I, since the resultant fuel pressure must act on the outer as well as the inner faces of valving pieces I 6 and Il for proper operation of the valve.

The valve guide section I6 has in its inner surface a circumferential recess 2| which is connected to the inlet pressure chamber I2 by orices 22 and 23. This structure is best shown in Fig. 3. The valve stem I8 has an axially extending bore 2li therein which cooperates with vent 25 and the radially and axially extending passageway 26 of valving piece I'I to form a fuel conduit from the circumferential recess 2I to tangential orifices 21 and 28, illustrated in Fig. 4, thereby connecting the inlet pressure chamber I2 to the outlet pressure chamber I3. The radially extending portion of the passageway 26 is closed at each end by the threaded pieces 29 and 30. Fuel from the inlet pressure chamber I2 is discharged through the tangential orices Z'I and 28 into the outlet pressure chamber I3 and the rotative torque developed on the valving piece I 'I rotates the movV able portions of the valve 'I and prevents sticking. Referring to Fig. 5, we have shown a modification of our invention illustrating an alternative meansV of connecting the inlet pressure chamber I2' with the outlet pressure chamber I3'. The connecting orifice 3| is located at the vertex of a conical indenture formed in the inner end surface of valve barrel 9'. In the modified valve, the inlet aperture I4 is located in the end piece I9 and the outlet aperture I5 is formed in end portion of valve barrel extension 32. VThis extension is threaded to valve barrel 9 as shown in Fig. 5 to form the outlet pressure chamber I3'. A spherical valving piece I'I' is threaded to the valve stem I8' which is shown in Fig. 5 as a part of a weighted valving piece IB in chamber I2. To secure the spherical valving piece il' to the valve stem I8', a nut 33 is threaded on the outer end of the valve stem I8 and keyed thereto by means of diametrical grooves 34 on the head of nut 33.

In operation, the fuel pump 4 provides the amount of fuel required at a pressure which is impressed upon the fuel along the fuel line to the valve 1 where the fuel pressure opens the valve to permit fuel flow. When the rotor is rotating, the fuel in the fuel line is also being rotated about the center of rotation and is consequently subjected to an additional pressure caused by the centrifugal forces of the fuel itself. The pressure due to this force increases along the fuel line and reaches a maximum at the tip of the blade. Thus, at any point in the fuel line the pressure is equal to the sum of the pressures caused by the centrifugal force plus that supplied by the fuel pump. It is desirable, however, that the fuel valve respond only to the fuel pump pressure. To accomplish this object, the valving pieces in the Valve are built of such mass that their centrifugal force balances the centrifugal pressure of the body or mass of fuel in the fuel line. Then, since the centrifugal force of the valving pieces oppose the centrifugal pressure of the fuel in the fuel line, the only unbalanced forces acting on the valving pieces I6, I'I are those exerted by the fuel pump pressure and the fuel outlet pressure. When the latter exceeds the fuel pump pressure, the resultant force acting on the valving pieces I6, l'I partially closes the vent 25, thereby reducing the amount of fuel transferred to the outlet pressure chamber and reduces the pressure therein. In operation, an equilibrium position is reached in which the amount of fuel transferred to the outlet pressure chamber I3 is just suicient to maintain the fuel outlet pressure equal to the fuel pump pressure. It will, of course, be obvious toone skilled in the art that the operation of the valve depends on the fuel inlet pressure exceeding the fuel outlet pressure by an amount sufficient to cause a transfer of fuel between pressure chambers I2 and I3. This pressure differential is equal to the centrifugal pressure of the fuel in the fuel line, and hence, the operation of the valve requires a minimum rotational speed of the fuel line 6.

The mode of operation of the modified valve shown in Fig. 5 is substantially the same as the above-described operation of the valve shown in Fig. 2, except that the fuel is transferred through the communicating aperture 3| instead of the valve stem bore 24.

Thus, while we have illustrated and described a particular embodiment of our invention, modifications thereof will occur to those skilled in the art. We desire it to be understood, therefore, that-our invention is not to be limited to theparticular arrangement disclosed, and we intend in the appended claims to cover all modifications which do not depart from the spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A fuel supply system for a reaction motor mounted on a rotor powered by said motor and comprising a fuel pump having an adjustable output pressure, a fuel line interconnecting said motor and said pump, said fuel line extending radially outward along said rotor so that due to rotation of said rotor the fuel pressure therein is affected by both the fuel pump pressure and r the centrifugal force acting on the fuel therein,

a fuel pressure responsive Valve interposed in said fuel line at substantially the same position as said motor for regulating the pressure between said pump and said motor, said valve comprising a valve barrel and a valve guide section located therein, a septum dividing said barrel into two pressure chambers, the first of said pressure chambers being connected to said fuel line by a fuel inlet aperture, and the seco-nd of said pressure chambers being connected `to said fuel line by a fuel outlet aperture, said first or inlet pressure chamber beingan outer chamber and said second or outlet'pressure chamber being an inner chamber with respect to the rotational axis of said rotor, a first valving piece located in said first pressure chamber and a second valving piece located in said secondV pressure chamber, a memlber connecting said valving pieces and supported in said valve guide section to permit axial movement thereof with respect to the valve barrel axis, such movement being radial with respect to the rotor axis, said valve guide section having a recess in its inner surface and an orifice for connecting said recess to said first pressure chamber, said connecting member having a bore therein and a vent providing communication between said bore and said recess when said valve is in an open position, said vent being gradually closed by axial movement outward of said connecting member, and said second valving piece.

being provided with a passageway providing communication between said second pressure chamber and said bore, the combined mass of said valving pieces and said connecting member being such'that their centrifugal force equals the centrifugal pressure of the fuel in said fuel line, whereby the pressure in said second or outlet pressure chamber depends upon the fuel pump pressure but is substantially unaffected by variations in the centrifugal force acting on the fuel.

2. A fuelsupply system for a reaction motor mounted on a rotor powered by said motor and comprising a fuel pump having an adjustable output pressure, a fuel line interconnecting said motor and said pump, said fuel line extending radially outward along said rotor soY that due to rotation of said rotor the fuel pressure therein is affected by both the fuel pump pressure and the centrifugal force acting on the fuel therein, a fuel pressure responsive valve interposed in said fuel line at substantially the same position asV said motor for regulating the pressure between said pump and said motor, said control valve comprising a valve barrel having a valve guide section therein, a septum dividing said barrel into two pressure chambers, the first of said pressure chambers being connected to said fuel line by a fuel inlet aperture, and the second of said pressure chambers being connected to said fuel line by a fuel outlet aperture, said rst or inlet i pressure chamber being an outer chamber and said second or outlet pressure chamber being an inner chamber with respect to the rotational axis of said rotor, a first valving piece located in said rst pressure chamber and a second valving piece located in said second pressure chamber, a member connecting said valving pieces and supported in said valve guide section to permit axial movement thereof with respect to the valve barrel axis, such movement being radial with respect to the rotor axis, said valve guide section having a recess in its inner surface and an orifice for connecting said recess to said first pressure chamber, said connecting member having a bore therein and a vent providing communication between said bore and said recess when said valve is in an open position, said vent being gradually closed by axial movement outward of said connecting member and said second Valving piece being provided with a passageway providing communication between said second pressure chamber and said bore, the opening of said passageway being substantially tangential to said connecting member so that fuel force therefrom creates a rotative torque on said second valving piece, the combined mass of said valving pieces and said connecting member being such that their centrifugal force equals the centrifugal pressure of the fuel in said fuel line, whereby the pressure in said second or outlet pressure chamber depends upon the fuel pump pressure but is substantially unaffected by variations in the centrifugal force acting on the fuel.

3. A fuel supply system for a reaction motor mounted on a rotor powered by said motor and comprising a fuel pump having an adjustable output pressure, a fuel line interconnecting said motor and said pump, said fuel line extending radially outward along said rotor so that due to rotation of said rotor the fuel pressure therein is effected by both the fuel pump pressure and the centrifugal force acting on the fuel therein,

6 a fuel pressure responsive valve interposed in said fuel line at substantially the same position as said motor for regulating the pressure between said pump and said motor, said control valve comprising a valve barrel having an apertured internal projecting section to divide said valve barrel into two pressure chambers, the first of said pressure chamber being connected to said fuel line lby a fuel inlet aperture, and the second of said pressure chambers being connected to said fuel line by a fuel outlet aperture, said first or inlet pressure chamber being an outer chamber and said second or outlet pressure chamber being an inner chamber with respect to the rotational axis of said rotor, a first valving piece located in said first pressure chamber and a second valving piece located in said second pressure chamber, a member connecting said rst and second Valving pieces and extending through said apertured internal projecting section, said aperture being proportioned for fuel passage between the limits of said aperture and said connecting member, said valving pieces and said connecting member being movable radially outward with respect to the rotational axis of said rotor to obstruct partially said aperture and thereby restrict the passage of fuel into said second pressure chamber, the combined mass of said valving pieces and said connecting member being such that their centrifugal force equals the centrifugal pressure of the fuel in said fuel line.

THOMAS B. MURDOCK. RICHARD H. BALL.

REFERENCES CITED UNITED STATES PATENTS Name Date Hroult Mar. 26, 1912 Number 

